I'm trying to make up an improved LED display to select and show the memory bank number it's on. At present I'm using a single digit LED display. I'd like to go to a two-digit display.

The 16 memory banks are presently selected using a 4029 up/down counter chip going to the expansion chip's 4 extra memory address lines. These 4 lines also input to a 4511 display encoder driver and 7-segment LED digit as the display.

In this instance, memories 0 to 7 (ie the first 8 memories) are displayed as 0 to 7 on the display. but because the 4511 display chip won't decode and display binary numbers past 9, I'm stuck with only accessing 0-9 memory banks. How would I make a 2-digit display to show the numbers 11-15? I'd rather not go down processor/PIC/Arduino solutions for this because I'm not into programming nor have the gear.

I notice that the 4029 chip has a "carry" feature. Is this what this is for? Access a 2nd 4511 chip for a cascading 2 digit display?

interesting,. I have an SK1 myself that still needs to be modified, and memory expension would be great
As for the displays, I wanted to drive a couple of displays a while back and if I remember correctly this either needed some special cmos/TTL chips
(which are no longer available) or a lot of extra logic which wasn't worth it in my opinion. So eventually I did use a PIC (not what you want).
So I'll keep my eye on this thread in case someone offers a solution.

Actually, yes, that's what I had been doing before I went with the 4029 counter - I had the 4511 hooked up to the lowest 3 address lines and the 4th to the dot. It's okay, and simple, but I just wanted something more aesthetic and user-friendly. If I can't find anything simple I'll go back to that.

Is there anyone out there that sells pre-programmed PIC chips to do this?

I'm amazed to find out how difficult it seems to be to do such a simple job. Surely there's some driver counter chip that simply overflows any number over 9 to another digit?

I recently built a two digit counter using the same IC's. there is an incorrect schematic somewhere on the web where the cascading will not work correctly. I'm away from home for a couple more days but I will check and see how I did this. I think you replicate your counter and decoder for the second display and take the carry out pin (pin 7) of the single digit/units, to the carry in pin (pin 5) of the double digit/tens. The reset pins of the two counters are tied to set the count to 00.

interesting,. I have an SK1 myself that still needs to be modified, and memory expension would be great ...

I've got an SK-5 which I would love to do a memory expansion on, but I'm not currently up to that standard . I'd be very interested in any postings on this subject as it may eventually give me the required knowledge to bite the bullet on that one! The 2-digit display should useful as well.

I'll watch this space...

Gary

P.S. I also have a PT-1 is pieces, which I'm planning to do some bending on. I've so far sprayed the (white) case black, so that usefully, you can't read what any of the buttons are for (didn't think that one through). I did this, because I was only going to use the keyboard for a tiny synth. I still might do this.

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